Doing design for objects other than the norm is usually fun challenge. Promotional products come in all shapes and sizes, and if you are slapping on more than just your logo there can be a lot of experiential things to consider. And don't forget that pesky technical requirements often work their way into the mix too.
In designing an "inspired conferencing mug" as a conference show giveaway I looked at a few different ways to make it an effective promotion. The slogan and doodles on a black mug, are carried over from an advertising campaign, so the overall branding is sound, and plays on the idea of a great conferencing venue inspiring great ideas. The interesting aspect is that while sitting at a meeting or conference with this mug, not only it is an advertisment and an object that will keep a viewer repeatedly engaged, but it may actually be inspirational on its own...leading to all sorts of doodles and brainstorming. Much more effective than just a plain mug with a logo.